Spec for V21 and/Or V22

- D
- Denis Gleeson
  
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posted
19 years ago

Mon, Sep 20, 2004 5:14 PM

Hi all

Im looking for the spec on V21 and/or V22 ccitt modem standards. I know they are in the blue book but I dont have it.

I found a post from 1991 saying that they were available for FTP from digital.resource.org:/pub/standards/ccitt/1992/v/ but Ive had no luck with this. Can anybody help.

Even if you have the blue book and would fax the V21 spec. Just the section on the communications sequence, frequencies etc.

Many thanks for any help.

Denis ___________________ FAX 00353 1 8531776 (just in case I get lucky)

- J
- John Woodgate
  
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posted
19 years ago

Mon, Sep 20, 2004 6:12 PM

I read in sci.electronics.design that Denis Gleeson wrote (in ) about 'Spec for V21 and/Or V22', on Mon, 20 Sep 2004:

You can download up to three ITU-T standards for free from the web site in any one year. There are a few which are exempted, though.

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The site is not very user-friendly; you may find you've bought them instead! Follow the instructions very carefully.

--
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

- H
- H. Peter Anvin
  
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posted
19 years ago

Tue, Sep 21, 2004 6:46 AM

Followup to: By author: snipped-for-privacy@utvinternet.com (Denis Gleeson) In newsgroup: comp.arch.embedded

CCITT V.21 uses:

Originate mark - 980 Hz Originate space - 1180 Hz Answer mark - 1650 Hz Answer space - 1850 Hz

It's simply FSK of a 300 bps asynchronous (RS-232) data stream; it can at least in theory be implemented completely as an analog device.

North America sometimes uses Bell 103 instead, which uses 1270/1070 and 2225/2025 for mark/space.

Here is a useful quick reference:

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-hpa